JPH0116591B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an injection molding or casting method and an apparatus for carrying out this method.

Methods for injection molding and casting metallic and non-metallic materials are already well known.

B. Prior Art/Problems to be Solved by the Invention Known methods and devices utilize pumping devices with mechanical pumps for pumping and metering liquefied molding or casting materials. . Such known devices are useful, especially since many molding or casting materials are controlled at liquidus temperatures, where they become extremely corrosive, and injection pressures reaching several hundred bars are becoming commonplace. , difficult to seal and prone to failure. Such devices are also difficult to start from cold, since the entire pumping device must be heated from the outside in order to liquefy the material within the pump.

C. Means for Solving the Problems The above technical means would make great progress if the pump mechanism described above could be omitted. SUMMARY OF THE INVENTION It is therefore an object of the invention to provide an injection molding or casting method and an apparatus for carrying out said method which eliminates the pumping mechanism described above.

In the injection molding or casting method according to the invention, a solid bar of the material to be molded or cast is subjected to the action of a plunger and heated in a heating chamber to a temperature higher than the melting or plasticizing temperature of the molding or casting material. The bar is pushed into a heating chamber so that its tip is melted or plasticized in the heating chamber, and the molten and plasticized material is discharged from the heating chamber through its opening. The method includes the step of discharging the molding material or casting material in a molten or plasticized state under pressure.

The discharge opening can be connected to an inlet opening of a mold or casting mold.

In the above method, molten or plasticized material is allowed to leak backwards along the bar from the heating chamber, and the leaked material around the solid bar is allowed to solidify, thereby solidifying around said bar inside the passageway. Forming a seal around the solid bar by forming a seal ring of molded or cast material can be included.

According to one aspect of the invention, the injection molding or casting method forces the molding or casting material through a straight passageway, the cross-sectional dimensions of the passageway being such that a clearance is provided between the bar and the heating the bar is sized to be slid into the passageway and introduced into the heating chamber while the chamber conditions are heated to a temperature above the melting or plasticizing temperature of the molding or casting material; Furthermore, a point closer to the heating chamber than the point where the melted or plasticized material from the heating chamber leaks and permeates in the opposite direction through the gap between the bar of molding or casting material and the passage due to the pressure in the heating chamber. The process includes maintaining the temperature below the melting point or plasticization temperature of the molding or casting material until the melting point or plasticization temperature of the molding or casting material.

According to another aspect of the invention, a bar of molding or casting material is slid through a straight channel and the inlet end of the bar is pushed into a heating chamber for gradual melting or plasticization. In the injection molding or casting method, a portion of the passage adjacent to the heating chamber leaks melted or plasticized molding or casting material into the gap between the bar and the passage under molding or casting pressure acting within the heating chamber. temperature conditions are set to maintain a temperature high enough to allow the material to enter the heating chamber, and a portion of the passageway further from the heating chamber than the adjacent circuit section is located at a temperature higher than that which could be reached by material leaking from the heating chamber. forming a seal against molding or casting material leaking from between the bar and the passageway by maintaining the temperature below the melting or plasticizing temperature of the casting or molding material up to a point close to the heating chamber; Contains.

A portion of the passage adjacent to the heating chamber and communicating with the passage may be formed to expand in diameter in a direction toward the heating chamber.

The method of the invention comprises a section of the passageway that is maintained at a temperature above the melting point or plasticization temperature of the molding or casting material and a section of the passageway that is maintained at a temperature below the melting point or plasticization temperature of the molding or casting material. can include the feature of maintaining a steep temperature gradient between parts of the

The point at which this steep temperature gradient occurs can be located between the ends of the enlarged diameter portion of the passageway.

This steep temperature gradient can be generated by a layer of insulation placed between the two sections of the passageway at the point where the steep gradient occurs.

The temperature of the material in the heating chamber can be set such that the material is in a molten or plasticized state. References to the "molten state" should be construed to include the slurry state.

An apparatus for carrying out the method of the invention has a body member formed with a straight passageway communicating with a heating chamber having a discharge opening, and a heating device for heating the material inside said heating chamber, the passageway being A portion of the formed body member and a bar of material to be molded or cast are slidably fitted within the passageway to act as a plunger, and a cooling device may be provided to cool the plunger.

A portion of the passage communicating with the heating chamber may be formed to expand in diameter in a direction toward the heating chamber.

The body member may be comprised of two sections interconnected in a plane substantially perpendicular to the axis of the passageway. If the passageway is formed with an enlarged diameter section, the plane may intersect the passageway at a location between the ends of the enlarged diameter section.

The two body parts can be interconnected with a heat insulating layer interposed therebetween. This thermal insulation layer can comprise at least one sheet of insulating material or several thin metal sheets.

Materials that can be continuously injection molded by the apparatus of the invention may be known zinc-based alloys. Most of these known alloys have a strong tendency to corrode certain metals, including steel, when in the liquid state at temperatures of about 450°C. If the main body of the device of the present invention is made of steel from the viewpoint of strength and cost, the walls of the passageway, heating chamber, discharge opening, etc. will contact the highly corrosive alloy, so these walls may be made of steel. For example, it may be chemically or electrically coated with a corrosion-resistant material such as chromium or tantalum.

The portion of the body forming the heating chamber may be surrounded by an induction heating coil, and the portion of the body forming the passageway may be surrounded by a jacket configured to contain a coolant, such as water.

The metallic insulation layer can also be selected to act as a screen against inductive heating that occurs in the cooled body portion.

D. Examples and operations Examples of the apparatus for carrying out the method of the present invention are illustrated in the accompanying drawings.

In the accompanying drawings, reference numeral 1 designates a body member in which a straight passageway 2 is formed. The passage 2 communicates with a heating chamber 3 from which a discharge opening 4 is formed. Reference numeral 5 indicates that the heating chamber 3 is heated so that induction heating is concentrated on the material sulfur in the heating chamber 3.
The coil of the induction heating device surrounds the coil of the induction heating device, and the reference numeral 6 designates a water jacket surrounding the part of the body member that formed the passageway 2. Reference numeral 7 designates a bar of molding or casting material arranged to be forced through the passageway 2 . The bar 7 is slid into the heating chamber 3 through the passage 2. Reference numeral 8 designates a part of the mold having an inlet opening 9 aligned with the discharge opening 4 of the body member 1 . Reference numerals 10 and 11 designate the inlet and outlet passages for the coolant introduced into the jacket 6.

In the structure of FIG. 2, the body member has passage 2
It consists of two parts 1A and 1B interconnected by a heat insulating layer 12 in a plane substantially perpendicular to the axis of. The end of the passage 2 leading to the heating chamber 3 is formed so as to expand in diameter toward the heating chamber 3, as indicated by reference numeral 13, and the heat insulating layer 12 is placed at a predetermined position between both ends of the expanded diameter portion. It is located. 1st
In the structure shown, reference numeral 14 designates molten material leaking from the heating chamber 3 into the part of the passage 2 between the wall of the passage 2 and the bar 7 at a short distance from the heating chamber 3. The leakage of material is caused by the pressure inside the heating chamber 3 when the bar 7 is pushed into the heating chamber 3. Further, in the structure shown in FIG.
3 and maintained in a molten state approximately up to the location of the insulation layer 12, the molten material being subsequently cooled and solidified in the enlarged diameter portion 13 on the other side of the insulation layer 12.

In practice, in the structure shown in FIG. 1, when the bar 7 is pushed forward, the tip of the bar 7 that has entered the heating chamber 3 is melted or plasticized in the heating chamber 3, and the bar 7 is is heating chamber 3
When pushed forward into the bar 7, it acts as a plunger and releases molten or plasticized material from the heating chamber 3 through the opening 4 and the mold 8.
into the mold recess through the inlet opening 9 of the mold. As the pressure of the material in the heating chamber 3 increases, a portion of the molten or plasticized material flows into the passageway 2.
Entering the gap between the wall and the bar 7 and penetrating a predetermined distance backwards from the heating chamber 3, the molten material finally reaches a portion of the channel 2 which is kept at a temperature below the melting or plasticizing temperature. reaches and solidifies,
As a result, a sealing ring is formed which surrounds the bar 7 and prevents further leakage and loss of pressure in the heating chamber 3. In the structure of FIG. 2, when the pressure in the heating chamber 3 increases, molten or plasticized material flows from the heating chamber 3 to the enlarged diameter portion of the passage 2.
3 and is moved along the enlarged diameter portion 13 to a position beyond the thermal fault 12. Due to the sharp temperature gradient created on both sides of the insulation layer 12, as the molten or plasticized material crosses the insulation layer 12, the molten material solidifies in the cooled portion of the enlarged diameter section 13 and seals the seal ring 16. Form. The seal ring 16 is in close contact with the cooling side of the heat insulating layer 12, that is, the portion of the enlarged diameter portion 13 on the side far from the heating chamber 3. When the bar 7 is moved forward, the bar 7 tends to move forward with the solidified sealing ring. Fresh molten material then flows behind the sealing ring to progressively form other sealing rings as the bar 7 moves forward, thereby maintaining the sealing action.
As new sealing rings are continually being formed, a continuous correction is made to the irregularities of the surface of the bar 7 along its length, thereby maintaining an effective sealing action. The solidified material forming the previous sealing ring that was moved forward into the heating chamber 3 is simply melted again and mixed with the material in the heating chamber 3. In the structure of FIG. 2, the size and position of the seal ring can be adjusted with high precision.

With the method of the invention, the bar of molten material or cast material acts as its own pump, so that there is no risk of leakage, and the movable material is free from leakage or failure and is corroded by the molding or casting material. High injection pressures can be used without the need to use equipment with sections.

[Brief explanation of drawings]

FIG. 1 illustrates an apparatus for carrying out the invention in its simplest form, and FIG. 2 illustrates an apparatus with enlarged diameter passages and a heat-insulating layer. DESCRIPTION OF SYMBOLS 1... Main body member, 1A, 1B... Two parts of main body member, 2... Passage, 3... Heating chamber, 4... Discharge opening, 5... Heating device, 6... Cooling device, 7
... Bar (plunger), 12 ... Heat insulation layer, 13
...Expanded diameter portion, 14...Melted material, 16...
Seal ring.

Claims (1)

[Claims] 1. A closed heating chamber 3 maintained at a temperature higher than the melting or plasticizing temperature of the molding or casting material using a solid bar 7 of the material to be molded or cast as a plunger. characterized in that the tip of the bar 7 is forced in so as to melt or plasticize in the heating chamber, and the molten or plasticized material of the pushed bar 7 is discharged from the heating chamber 3 through the discharge opening 4 Heating chamber 3
An injection molding or casting method comprising the step of pressurizing and discharging a molding material or casting material in a molten state or a plasticized state from a discharge opening 4. 2. In the injection molding or casting method according to claim 1, the molten or plasticized material is moved backward from the heating chamber 3 along the bar 7 to a predetermined point on said bar outside the heating chamber 3. Let it leak,
and forming a seal around the solid bar 7 by solidifying the leaked material surrounding the bar 7 at said predetermined points, thereby forming a sealing ring 16 of solidified molded or cast material around the bar 7. An injection molding or casting method characterized by forming. 3. In the injection molding or casting method as claimed in claim 2, a solid bar 7 is forced through a straight passage 2 communicating with a heating chamber 3, said passage 2 being formed between the bar 7 and the wall of the passage. with a gap therebetween and cross-sectional dimensions such that the bar 7 is a sliding fit in the passageway, and furthermore, the bar 7 in the passageway 2 is heated by the molten or plastic material from the heating chamber 3. below the melting or plasticizing temperature of the molding or casting material, up to a point closer to the heating chamber 3 than the melted material can penetrate by leaking in the opposite direction through said gap due to the pressure in the heating chamber 3. An injection molding or casting method characterized by maintaining low temperatures. 4 In the injection molding or casting method according to claim 3, the passage 2 adjacent to the heating chamber 3
maintained at a sufficiently high temperature to cause the molten or plasticized molding or casting material to leak into the gap between the bar 7 and the passage 2 due to the molding or casting pressure in the heating chamber 3; The temperature conditions are set so that the casting material or the molding material is An injection molding or casting process characterized by maintaining the temperature below the melting point or plasticization temperature of. 5. In the injection molding or casting method as claimed in claim 4, the molding or casting material is A portion of the passageway 2 maintained at a temperature above the melting point or plasticization temperature and a portion of the passageway 2 maintained at a temperature below the melting point or plasticization temperature of the molding or casting material.
An injection molding or casting method characterized by maintaining a steep thermal gradient between the parts. 6 a body member 1 formed with a straight passage 2 communicating with a heating chamber 3 having a discharge opening 4; a heating device 5 for heating the material inside the heating chamber 3;
A plunger 7 formed as a bar of the material to be molded or cast is located in the passage 2 in an apparatus for carrying out an injection molding or casting operation. A device characterized in that it is a sliding fit. 7. The device according to claim 6, wherein the portion 13 of the passage 2 communicating with the heating chamber 3 is formed to expand in diameter in the direction toward the heating chamber 3. 8. A device according to claim 6, in which the body member 1 comprises two parts 1 interconnected in a plane substantially perpendicular to the axis of the passageway 2.
A device characterized by comprising A and 1B. 9. In the device according to claims 7 and 8, the two parts 1A, 1 of the main body member 1
A device characterized in that the plane to which B is connected intersects the passage 2 at a position between both ends of the enlarged diameter portion 13. 10 In the device according to claim 8, the two portions 1A and 1B of the main body member are provided with a heat insulating layer 1.
A device characterized in that the device is interconnected by two.